In today's electrical supply systems, there are occasions when alternate sources of electrical power are necessary or desirable. For example, the capability of switching from utility power to emergency generator power is very important for many businesses, hospitals and industries, and is also being employed in residential applications.
In certain applications, it is desirable for separate electrical circuits or even separate groups of electrical circuits to be arranged so that when one group of circuits is switched to a conductive state, another group of circuits is switched to a non-conductive state in alternating fashion. In some arrangements, it may be desirable to alternately switch a common load between separate power sources so that, as one power source is disconnected from the load, the second power source is connected to prevent interruption of power to the load. In order that the alternate switching may be effective essentially simultaneously, a need has been recognized to employ a coupling mechanism which functions to switch one circuit OFF as the other circuit is switched ON. Prior art interlocking systems provide an interlock for first and second aligned circuit breakers having first and second external operating handles oriented thereon such that the operating handles are parallel and disposed away from each other when the switches are OFF, and towards each other when the switches are ON. The interlock includes a linkage arrangement disposed across the face of the circuit breaker switches for applying a linear force between the first operating handle and the second operating handle. The linkage arrangement is formed such that pushing the first operating handle from an OFF position to an ON position pushes the second operating handle from an ON position to an OFF position. An example of an interlock of this type is disclosed in Flegel U.S. Pat. No. 5,648,646 issued Jul. 15, 1997.
The above-described interlock functions satisfactorily for switches which have parallel handles and which move along a common axis between their ON and OFF positions. However, it is common to feed utility or primary power to a load center through a main circuit breaker which is oriented perpendicularly to the branch circuit breakers. With this arrangement, the switch handle of the main circuit breaker moves between its ON and OFF positions in a direction perpendicular to the direction of movement of the branch circuit breaker switch handles. This construction prevents use of known prior art interlocks with the main circuit breaker, since known interlocks can only be used with aligned switch handles which move along a common axis.
It is thus desirable to provide an interlock mechanism which prevents two circuit breakers in nonparallel relation to each other, and possibly of different sizes, from being turned ON simultaneously. It is also desirable that the interlock mechanism permits both of the circuit breakers to be switched OFF at the same time.
Accordingly, it is an object of the present invention to provide a circuit breaker interlock which is useable when the circuit breakers have switches operational in transverse directions. A further object of the invention is to provide an interlock that prevents two power sources from supplying power to an electrical panel simultaneously. Yet another object of the invention is to provide an interlock that allows the circuit breakers to reside simultaneously in an OFF position so that no power is supplied to the electrical panel. Yet another object of the invention is to provide an interlock that is easily adaptable to commonly available circuit breakers and electrical panels. Yet another object of the invention is to provide an interlock which is relatively simple in its components and construction, and adaptable to other switching applications.